The makers of Blue Buffalo pet foods are recalling certain lots of the company’s Wilderness Chicken-Dog, Basics Salmon-Dog and Large Breed Adult Dog products due to fears that the food may contain higher levels of vitamin D than are specified.

The problem, officials say, likely stems from what appears to be a glitch tied to one of the company’s dry ingredients suppliers concerning a form of vitamin D that’s not supposed to be in the Blue Buffalo foods in question.

The U.S. Food and Drug Administration is expected to soon issue a public notice on the recall. According to the company, the following production runs distributed to pet specialty stores nationwide are involved:

Any unused product still in its bag may be returned to the point of purchase for a full refund.

In an announcement issued this afternoon, officials with Wilton-Conn.-based Blue Buffalo reveal 36 cases nationwide of dogs with symptoms consistent with elevated levels of vitamin D in their systems while on the diets, with symptoms resolving after being switched to a different brand of food. Practitioners have reported many of those cases on the Veterinary Information Network, or VIN, an online community for the profession and parent of the VIN News Service.

Hypervitaminosis D induces bone loss and abnormally high serum calcium levels, which could result in kidney stones and the calcification of organs like the heart and kidneys if left untreated. Hypercalcemia often is associated with certain forms of cancer, which could lead a pet owner to choose euthanasia upon hearing such a potentially grave diagnosis.

In late August, the VIN News Service published an article citing reports of hypervitaminosis D symptoms in dogs fed a diet of Blue Buffalo, mainly its chicken flavors. Newer cases are associated with the Basics Salmon formulation.

VIN members have been trying to discern whether reports of hypercalcemia secondary to vitamin D toxicosis occurring in dogs that eat Blue Buffalo were either a coincidence or a problem with the pet food. In each of the cases, the dogs improved rapidly upon receiving a change in diet.

Though months of testing and investigation by Blue Buffalo showed no unusual amounts of vitamin D in their products, company officials now report that the manufacture of a vitamin D supplement on the same equipment that produced the pet food likely caused the problem.

“We came to this conclusion after discovering that our ingredient supplier had made a scheduling error and produced a vitamin D supplement immediately prior to preparing the ingredients for the Blue products that are in question. We believe that some of the vitamin D supplement may have been carried over into our products, resulting in more vitamin D than is called for in our formulas,” the company’s website states.

A veterinarian who works with Blue Buffalo posted a more technical and in-depth explanation of the problem to his colleagues in a VIN message board discussion, though the VIN News Service could not immediately obtain his permission to publicly relay the information.

Dr. Joy Mueller, a veterinarian in Santa Rosa, Calif., who identified the condition in her two-year-old Australian shepherd, is relieved that the problem is being taken seriously. Before being taken off the diet, she reports that her dog had become lethargic, producing copious amounts of extremely dilute urine and drinking large amounts of water.

“I’m pleased they’re doing a recall,” she says. “Blue Buffalo is really stepping up to the plate, and I have to give them kudos for the hard science that they did to figure this all out. I think that they are a very conscientious company.”

In a news release issued on Friday to the Associated Press, Blue Buffalo’s Richard MacLean, vice president of business affairs, instructs owners with dogs that show signs of lethargy or exhibit unusually frequent water consumption or urination to immediately contact a veterinarian.

“In all cases the symptoms have subsided upon discontinuing feeding these products with no apparent long-term health consequences,” the release states.

Consumers who have incurred expenses for veterinary services and/or laboratory testing fees related to the recalled products can call the Blue Buffalo customer service department at (877) 523-9114 for reimbursement.

Blue Buffalo representatives will contact clients of veterinarians who have already submitted related expenses to the company.

VIN News Service commentaries are opinion pieces presenting insights, personal experiences and/or perspectives on topical issues by members of the veterinary community. To submit a commentary for consideration, email news@vin.com.